1. Field of the Invention
The present invention generally relates to catalysts and more particularly relates to a method of providing an improved hydrogenation catalyst employing a very low concentration of selected metal.
2. Prior Art
Various types of hydrogen electrodes for metal-hydrogen electrochemical cells were originally developed for alkaline fuel cells and are commercially available. Those fuel cell electrodes invariably consist of an active catalyst material which is either platinum or palladium deposited with a binder on a thin conducting screen. Typically, the catalyst material is present in a substantial concentration; for example, when the catalyst is platinic oxide it may contain 9 mgs of platinum per square centimeter and in many instances contains substantially more platinum than that. One such typical fuel cell electrode has platinum black in a concentration of about 9 grams per sq. ft. in a polytetrafluoroethylene binder with a 70 mesh nickel screen backing the catalyst. Such electrodes are disclosed in U.S. Pat. Nos. 3,990,910, 3,444,004, 3,533,851, 3,553,022 and 3,432,355.
Hydrogen electrodes which are designed primarily for use in fuel cells in the anodic mode, that is, only for discharging, as compared with nickel-hydrogen usage where the electrode must be used for both charging and discharging, exhibit severe shortcomings when operated in a long term cycling mode. It would therefore be desirable to provide an improved, more efficient rechargeable metal-hydrogen electro-chemical cell.
Various types of catalysts have been used for the hydrogenation of such organic compounds as acetone and methylethyl ketone to the corresponding alcohols. Other catalysts have been employed in the hydrogenation of aldehydes, aliphatic and aromatic nitro compounds and carbon double bonds. Still other catalysts have been utilized in the oxidation of formaldehyde and formic acid. It would be desirable to provide an improved catalyst which could function efficiently for a number of such reactions, as well as exhibiting very high activity in a metal-hydrogen electrochemical cell.